Ruddspeed Conversion

[TodE]

I purchased a 1962 BT7 original Tri Carb that the previous owner changed over to the Ruddspeed conversion with 3 HS6 carbs. When I purchased the car it had not been run that much. I put about 60 miles on the car not getting on it that much to break the engine in.
When the plugs were pulled they were very fouled with heavy black soot on all the spark plugs. When the needles were pulled it was noted that they used the regular HS6 needles which made the mixture too rich. Has anybody done this conversion or have a knowledge on the correct needles to use?
Also does anyone have any technical literature on the Ruddspeed conversion that they could email me or fax me?

Maybe Dougie could comment as I think he has the conversion with HD8 carbs?


Thank you,

Tod

 

[Michael Oritt]

Tod--

You might want to google "SU Needle Program" and follow the instructions which may give you some rough indicators on needles from which you could proceed. The info is rather generic but I used it with some success whnen I changed from a cast to tubular intake manifold on the Elva and had to find a leaner needle.

 

[GregW]

I don't know how many programs are out there, but here is one.
Win SU

 

[dougie]

TodE -

The Ruddspeed manifold is designed to provide the air/fuel mixture into the combustion camber
at a faster more efficient rate. If you're fouling plugs with the standard needles I would look at other factors. Timing or the heat range of plugs you're running could be an issue. Also make sure you fill the tank with fresh gas and run it for a while down the freeway, then read the plugs.

I run custom made needles a couple steps past the recommended rich version. My modified triple 2" SU HD8's and flowed iron head pulls a lot of air though.

 

[johnea]

TodE,

My car is a Ruddspeed converted BN6 using tripple HD6 carbs. A Dynotest revealed that the standard needles were too rich. The lean needle listed for the standard BN6 was in my case the correct needle for this setup. Ruddspeed never suggested using other needles than standard to my knowledge

 

[Patrick67BJ8]

It escapes me where I've seen information on setting up Ruddspeed carbs withneedle selection with different cams and performance write-up, but I believe it was a UK web-site. I have the info saved on another computer.
It was very detailed an informative and will help you sort out your problems.
I have not tried it out yet but I have a brand new Ruddspeed manifold and two sets of HD6's and maybe someday I might use them(and maybe not) on my BJ8.
Patrick

 

[Patrick67BJ8]

TodE,
Here's the "paper" from the UK Austin Healey Clu "tech" link. Go to the site for better looking papers.
Patrick

Austin Healey 3000 Tri-Carb Setup & Camshafts.
This page is intended to give some help to those like myself who are interested in tuning the AH 3000 engine for road use. The information is based on my own research and findings, and neither myself nor the Austin Healey Club UK can take any responsibility for the accuracy of the information, or any consequences of it's use.

The 3000 engine effectively appeared in four different guises relating to camshaft and carburetor specifications:

AH3000 Model Standard Engine Setup
Model 3000 MKI 124bhp 3000 MKII 133bhp 3000 MKIIA (BJ7) 132bhp 3000 MKIII (BJ8) 148bhp
Camshaft timing 230 degree duration 230 degree duration 240 degree duration 252 degree duration
Carb setup 2 x 1.75" HD6 (0.100" jet) 3 x 1.5" HS4 (0.090" jet) 2 x 1.75" HS6 2 x 2.0" HD8
Needles Std-CV; Weak-SQ; Rich-RD Std-DJ; Weak-DH; Rich-DK Std-BC; Weak-TZ; Rich-RD Std-UH; Weak-UL; Rich-UN
Dashpot spring AUC 1170, Type A-Green, 12oz AUC 4387, Type A-Red, 4.5oz AUC 1170, Type A-Green, 12oz AUC 4826, Type A-Red/Green, 11.25oz

Modified Engine: 3 x HD6 (1.75") Carbs
The use of three HD8 2" carbs is well documented, all three having the same needles (UH) and dashpot springs as the standard setup. However, I have not been able to locate any data for triple 1.75" carbs. In my case, the attraction of this setup was that I already had the two standard HD6 carbs and a set of standard MKII inlet manifolds. These manifolds can be opened out from 1.5 to 1.75" diameter but no further. Fitting triple 2" HD8s requires larger, after-market, manifolds.

The following charts my experiments with different carburetor settings, first on an engine fitted with a BJ8 profile cam, then on my second engine with a Denis Welch DWR8 cam; details of which are given below. Both engines have a branch exhaust manifold fitted whilst the second engine also has an alluminium head and Omega forged pistons.

3 x HD6 Carbs with BJ8 camshaft (252 deg.)
Needles Dashpot spring Comments
CV (MKI Std needle) AUC 4387, Type A-Red, 4.5oz Rich low/mid range causing plugs to foul
SQ (MKI weak needle) AUC 4387, Type A-Red, 4.5oz OK but a bit flat in the mid range
BC (MKII Std needle) AUC 4387, Type A-Red, 4.5oz OK
TZ (MKII weak needle) AUC 4387, Type A-Red, 4.5oz Very flat low/mid range


3 x HD6 Carbs and a Denis Welch DWR8 camshaft (278 deg.) (see camshaft data below)
Needles Dashpot spring Comments
BC (MKII Std needle) AUC 4387, Type A-Red, 4.5oz A bit rich, lumpy low range, blackish exhaust
SQ (MKI weak needle) AUC 4387, Type A-Red, 4.5oz Good, a bit lumpy low/mid range on part throttle
SQ (MKI weak needle) AUC 1167, Type A-Yellow, 8oz* Good
TZ (MKII weak needle) AUC 1167, Type A-Yellow, 8oz OK, smoother low/mid range, low power
RK AUC 1167, Type A-Yellow, 8oz Feels a bit rich, sluggish
TL AUC 1167, Type A-Yellow, 8oz OK some slight misfire at low speed part throttle. Poor when cold.


* Using a straightened paper clip through the breather hole in the top of the dashpot top and a bit of masking tape to stop it sliding under it's own weight, a full throttle blast indicated that the piston was reaching it's full travel with this spring.

In conclusion, I found the BC needle to be best with the BJ8 camshaft, and the SQ needle best with the DWR8 camshaft.

The following chart below gives a comparison of the annulus area for each needle, i.e. the area between the needle and the jet, at each stage of the needle travel. The measurements are equalised at position 2 which is about the idle position. For needle data go to this Triumph site by Teglerizer Engineering



Austin Healey 3000 Camshafts:
MAKE REF LIFT DURATION INLET EXHAUST COMMENT
mm ins btdc abdc bbdc atdc
AH MKI 8.054 0.3145 230 5 45 40 10
AH MKII 9.35 0.368 230 5 45 51 21
AH MKIIA 9.35 0.368 240 10 50 45 15
AH MKIII AEC865 9.35 0.368 252 16 56 51 21
Piper BP270 10.16 0.400 272 29 63 64 28
Kent AH2 10.44 0.411 278
Denis Welch ENG656/7 9.35 0.368 268
Denis Welch DWR8 10.9 0.430 278 33 65 63 31 requires pocketed block & 0.15" valve clearance
SC Parts SC6614 11.48 0.452 300 50 70 75 45 Requires Webers (note as MGB Race AEH770)